O45-regulation of osteoblast differentiation and ECM remodeling by Bmp2/4 in vitro

Both of bone morphogenetic proteins 2 and 4 (Bmp2 and Bmp4) are two closely related members of the transforming growth factor beta superfamily and play diverse roles in normal and pathological processes. However, detail understandings of mechanisms through which Bmp2 and Bmp4 exert their effects remain elusive due to their functional compensations each other. To study roles of Bmp2/Bmp4 in osteoblast differentiation and extracellular matrix (ECM) remodeling, calvarial osteoblasts from Bmp2/4 conditional mice with Cre recombinase recognition site (loxP) were isolated and transfected with simian virus 40 large T antigen to generate immortalized BMP2C/C4C/C (iBMP2 C/C/4C/C) osteoblast lines. The BMP2/4 genes in the iBMP2 C/C/4C/C cells were double knocked out by Ad-Cre recombinase infection. Differentiation and mineralization of iBMP2C/C/4C/C knock-out (iBmp2C/C/4C/C KO) cells were detected by alkaline phosphatase (ALP) and alizarin (ALZ) red S staining analyses. ECM remodeling was also observed in fluorescent microscope. Cell differentiation was dramatically decreased in the iBMP2C/C/4C/C KO cells compared to that of the iBMP2C/C/4C/C osteoblasts. Mineralization was also reduced in these KO cells by ALZ staining. Furthermore, Bmp2/4 double knock-out cells have major defects in remodeling the ECM as reflected by changes in collagen type I processing. Here we for the first time demonstrate the establishment of iBmp2C/C/4C/C KO osteoblasts. Cell differentiation and mineralization in the iBmp2C/C/4C/C KO cells were decreased. Furthermore, ECM processing in these KO cells was impaired. This indicates that BMP2/4 play important roles in osteoblast differentiation and ECM remodeling.

Assessment of the effect of selected snack foods on the remineralization/demineralization of enamel and dentin

This study utilized volunteer subjects to examine caries-like lesions for remineralization and demineralization patterns in dentin and enamel when nine different snack foods were eaten between meals. Caries progression was observed in enamel and dentin when apple juice, a cola beverage, and sweetened (strawberry) yogurt were consumed as snacks. Remineralization of enamel was observed when cheddar cheese, skim milk, 2% milk, whole milk, chocolate milk, and orange juice were used as between meal snacks. Dairy products, with the exception of the sweetened yogurt, generally reduced the amount of demineralization produced in dentin. This study helps establish a scientific basis for appropriate between-meal snacks for patients who are concerned about their dietary habits as a part of their overall preventive oral health plan.

The effect of locally delivered controlled-release doxycycline or scaling and root planing on periodontal maintenance patients over 9 months

BACKGROUND

This research report evaluates clinical changes resulting from local delivery of doxycycline hyclate (DH) or traditional scaling and root planing (SRP) in a group of patients undergoing supportive periodontal therapy (SPT).

METHODS

In all, 141 patients received either DH (67) or SRP (74) treatment in sites > or =5 mm on one-half of their dentition at baseline and month 4.

RESULTS

Clinical results were determined at month 9. Baseline mean probing depth recordings were similar between the two groups (DH = 5.9 mm; SRP = 5.9 mm). Mean month 9 results showed similar clinical results for attachment level gain (DH 0.7 mm; SRP 0.8 mm) and probing depth reduction (DH 1.3 mm; SRP 1.1 mm). Percentage of sites showing > or =2 mm attachment level gain at month 9 was 24.7% in the DH group and 21.2% in the SRP group. Thirty-nine percent (39%) of DH sites and 38% of SRP sites showed > or =2 mm probing depth reduction. When treated sides of the dentition were compared to untreated sides, DH showed a difference in disease activity (> or =2 mm attachment loss) from 19.3% (untreated) to 7.2% (treated); and SRP from 14.3% (untreated) to 8.1% (treated).

CONCLUSIONS

Results show that both DH without concomitant mechanical instrumentation and SRP were equally effective as SPT in this patient group over the 9-month study period.

Effects of smoking on local delivery of controlled-release doxycycline as compared to scaling and root planing

This paper examines the effects of smoking on the treatment outcomes of two nonsurgical therapies: (1) scaling and root planing alone (SRP) or (2) controlled-release of subgingivally delivered doxycycline hyclate in a polylactic acid based polymer gel. Subjects from 2 9-month multicenter studies were classified as nonsmokers (never smoked: 100 subjects), former smokers (137 subjects), and current smokers (> or = 10 cigarettes/day: 121 subjects). Clinical parameters were analyzed for treated sites with baseline probing depths > or = 5 mm and for a subset of treated sites with baseline probing depths of > or = 7 mm. Clinical parameters (plaque levels, clinical attachment levels, pocket depths, and bleeding on probing) were analyzed at baseline, 4, 6, and 9 months. In the doxycycline treated group in general, there were neither marked significant differences in clinical attachment gain nor differences in probing depth reduction among the 3 smoking groups. On the other hand, in the scaling and root planing treated group in general, there were significant differences in clinical attachment gain and pocket depth reduction, with non-smokers responding better than former smokers and current smokers at 6 and 9 months. These differences in clinical response between scaling and root planing alone versus controlled-release of locally-delivered doxycycline hyclate among these 3 smoking groups are discussed in relation to treatment implications for smokers.

Two multi-center studies evaluating locally delivered doxycycline hyclate, placebo control, oral hygiene, and scaling and root planing in the treatment of periodontitis

BACKGROUND

The clinical efficacy and safety of doxycycline hyclate (8.5% w/w) delivered subgingivally in a biodegradable polymer (DH) was compared to placebo control (VC), oral hygiene (OH), and scaling and root planing (SRP) in 2 multi-center studies.

METHODS

Each study entered 411 patients who demonstrated moderate to severe periodontitis. Patients had 2 or more quadrants each with a minimum of 4 qualifying pockets > or =5 mm that bled on probing. At least 2 of the pockets were > or =7 mm. Treatment with DH, VC, OH, or SRP was provided at baseline and again at month 4. Clinical parameters were recorded monthly.

RESULTS

DH and SRP resulted in nearly identical clinical changes over time in both studies. Mean 9 month clinical attachment level gain (ALG) was 0.8 mm for the DH group and 0.7 mm for the SRP group in Study 1, and 0.8 mm (DH) and 0.9 mm (SRP) in Study 2. Mean probing depth (PD) reduction was 1.1 mm for the DH group and 0.9 mm for the SRP group in Study 1 and 1.3 mm for both groups in Study 2. Frequency distributions showed an ALG > or =2 mm in 29% of DH sites versus 27% of SRP sites in Study 1 and 31% of DH sites versus 34% of SRP sites in Study 2. PD reductions > or =2 mm were seen in 32% of DH sites versus 31% of SRP sites in Study 1 and 41% of DH sites versus 43% of SRP sites in Study 2. Comparisons between DH, VC, and OH treatment groups showed DH treatment to be statistically superior to VC and OH. Safety data demonstrated a benign safety profile with use of the DH product.

CONCLUSIONS

Results of this trial demonstrate that treatment of periodontitis with subgingivally delivered doxycycline in a biodegradable polymer is equally effective as scaling and root planing and superior in effect to placebo control and oral hygiene in reducing the clinical signs of adult periodontitis over a 9-month period. This represents positive changes resulting from the use of subgingivally applied doxycycline as scaling and root planing was not limited regarding time of the procedure or use of local anesthesia.

In vitro demineralization-remineralization of enamel caries at restoration margins utilizing fluoride-releasing composite resin

The release of fluoride from a composite resin has been shown to inhibit enamel demineralization. The purpose of this study was to examine the remineralization effects of a fluoride-releasing resin. Twenty extracted molars were painted with an acid-protective varnish, excluding a 2 x 6-mm window. Artificial carieslike lesions were created in the exposed enamel with an acidified gel. A Class II preparation was restored with a fluoride-releasing or a non-fluoride-releasing composite resin. The teeth were sectioned longitudinally and photographed with polarized light microscopy in water and Thoulet's imbibition media. The sections were then painted with an acid-protective varnish, so that only the natural external surface of the lesion was exposed, and placed in separate closed environments of a nonfluoridated artificial saliva. Sections were removed after 2 weeks and 3 months and photographed under polarized light as before. A sonic digitizer was used to measure the area of the body of the lesion. Results demonstrated a statistically significant area reduction in the body of the lesions exposed to the fluoridated composite resin at 2-week and 3-month intervals.

The effectiveness of electronic dental anesthesia in children

This study compared the effectiveness of traditional local anesthesia with a Transcutaneous Electrical Nerve Stimulation unit that controls pain via electronic dental anesthesia for restorative dental procedures in 6- to 12-year-old children. The sample included 27 children who had two antimere teeth that required restorations of similar size (preventive resin restorations). In each case, the cavity preparation extended into dentin. One of the teeth was treated with conventional local anesthesia and the other with EDA. Selecting which tooth and which method to complete first was done randomly. Both restorations were done at the same appointment. Throughout the procedure, the child was asked to assess the level of discomfort using the Eland Color Scale, which allowed the children to draw on their past painful experiences to judge the level of pain they perceived. The patients demonstrated no overall significant difference in pain perception between the two modalities of treatment, regarding dentin sensitivity and rubber dam clamp replacement. When asked which method they preferred after the study, 78% of the patients chose EDA over local anesthesia.